River hydrological seasonality influences life history strategies of tropical riverine fishes

Under a particular set of selective forces, specific combinations of traits (strategies) will be favored in a given population, within the particular constraints of the considered species. For fishes, three demographic strategies have been suggested to result from adaptive responses to environmental predictability (i.e., seasonality): periodic, opportunistic and equilibrium [Winemiller KO, Rose KA (1992) Patterns of life-history diversification in North American fishes: implications for population regulation. Can J Fish Aquat Sci 49:2196–2218]. These strategies optimize fitness within predictable, unpredictable and stable systems, respectively. We tested these predictions of life history trait distribution along a gradient of hydrologic seasonality in West African tropical rivers at the drainage basin scale. We used logistic regression of species presence–absence data to test whether dominant life history traits of species caused community compositional change in response to a gradient of seasonality in hydrologic regime across basins. After accounting for taxonomic relatedness, species body size and statistical redundancy inherent to related traits, we found a higher proportion of species producing a great number of small oocytes, reproducing within a short period of time and presenting a low degree of parental care (the periodic strategy) in highly seasonal drainage basins (e.g., rivers with a short and predictable favorable season). Conversely, in more stable drainage basins (e.g., rivers with a wet season of several months), we observed a greater proportion of species producing small numbers of large oocytes, reproducing within a long period of time and providing parental care to their offspring (the equilibrium strategy). Our results suggest that distributions of tropical freshwater fishes at the drainage basin scale can be partly explained by the match between life history strategies and seasonality gradients in hydrological conditions. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Intergroup conflicts among chimpanzees in Taï National Park: lethal violence and the female perspective

Intercommunity aggression in chimpanzees and primitive warfare in humans possess striking similarities, such as the common occurrence of large male coalitions, systematic control of territory boundaries, and lethal attacks on isolated individuals from neighboring groups. However, an important apparent contrast is the absence of recurrent peaceful interactions between neighboring groups of chimpanzees. We observed a remarkable range of behavior in intergroup encounters among three habituated communities of chimpanzees in Taï National Park, Côte d'Ivoire. Lethal attacks are documented in these study groups for the first time, as well as year‐long exchanges of parous adult females and peaceful intergroup visits of mothers with infants. Demographic factors, including group size and number of adult males, are shown to affect the nature of intergroup interactions in ways not considered previously. A reconsideration of the difference in intergroup interactions between eastern and western chimpanzees is proposed including a more important consideration of the female's perspective. The inclusion of the new complexities in intergroup interactions in chimpanzees allows new parallels to be drawn with the evolution of primitive warfare in humans. Am. J. Primatol. 70:519–532, 2008. © 2008 Wiley‐Liss, Inc.     

Home Garden Production and Energetic Sustainability in Calakmul,Campeche, Mexico

Energy flows were studied for the 2002–2003 agricultural cycle in four households for which agriculture is part of a diversified survival strategy and four that practice agriculture as a business. Home garden inputs and outputs were measured monthly. Quantified inputs were: household labour, household agro-system production, and purchased external renewable and non-renewable energy. Outputs measured were: sales, family and animal foods. While both strategies had similar indicators in biomass and energy production, vegetable richness, and soil quality, household garden function and sustainability differed between subsistence and commercial householders. Subsistence gardens complemented family diet and contributed to household system resiliency. They relied heavily on renewable energy sources from within their agro-system. Gardens in commercial households reduced fruit tree area and increased animal husbandry for the market. They depended more on purchased non-renewable energy sources and were less sustainable and much less energy efficient than traditional gardens.

甘肃甘南藏族自治州生态环境现状与恢复对策

甘南藏族自治州生态环境状况,对于保障黄河、长江中下游地区生态安全具有重要作用。受多种因素影响,该地区生态环境受到严重破坏。在资料查阅、实地考察与访谈的基础上,阐述了甘南藏族自治州生态环境的现状,分析了产生这种现状的原因,最后提出了重建对策。     

Divergence in parental care, habitat selection and larval life history between two species of Peruvian poison frogs: an experimental analysis

Changes in the nature of the ecological resources exploited by a species can lead to the evolution of novel suites of behaviours. We identified a case in which the transition from large pool use to the use of very small breeding pools in neotropical poison frogs (family Dendrobatidae) is associated with the evolution of a suite of behaviours, including biparental care (from uniparental care) and social monogamy (from promiscuity). We manipulated breeding pool size in order to demonstrate experimentally that breeding habitat selection strategy has evolved in concert with changes in parental care and mating system. We also manipulated intra- and interspecific larval interactions to demonstrate that larval adaptation to the use of very small pools for breeding affected the evolution of larval competition and cannibalism. Our results illustrate the intimate connection between breeding pool ecology, parental care and mating strategies in Peruvian poison frogs.     

Distinguishing four fundamental approaches to the evolution of helping

The evolution and stability of helping behaviour has attracted great research efforts across disciplines. However, the field is also characterized by a great confusion over terminology and a number of disagreements, often between disciplines but also along taxonomic boundaries. In an attempt to clarify several issues, we identify four distinct research fields concerning the evolution of helping: (1) basic social evolution theory that studies helping within the framework of Hamilton's inclusive fitness concept, i.e. direct and indirect benefits, (2) an ecological approach that identifies settings that promote life histories or interaction patterns that favour unconditional cooperative and altruistic behaviour, e.g. conditions that lead to interdependency or interactions among kin, (3) the game theoretic approach that identifies strategies that provide feedback and control mechanisms (protecting from cheaters) favouring cooperative behaviour (e.g. pseudo-reciprocity, reciprocity), and (4) the social scientists' approach that particularly emphasizes the special cognitive requirements necessary for human cooperative strategies. The four fields differ with respect to the 'mechanisms' and the 'conditions' favouring helping they investigate. Other major differences concern a focus on either the life-time fitness consequences or the immediate payoff consequences of behaviour, and whether the behaviour of an individual or a whole interaction is considered. We suggest that distinguishing between these four separate fields and their complementary approaches will reduce misunderstandings, facilitating further integration of concepts within and across disciplines.     

Virus-host Interactions during Hepatitis C Virus Entry - Implications for Pathogenesis and Novel Treatment Approaches

Hepatitis C virus (HCV) is a member of the Flaviviridae family and causes acute and chronic hepatitis. Chronic HCV infection may result in severe liver damage including liver cirrhosis and hepatocellular carcinoma. The liver is the primary target organ of HCV, and the hepatocyte is its primary target cell. Attachment of the virus to the cell surface followed by viral entry is the first step in a cascade of interactions between the virus and the target cell that is required for successful entry into the cell and initiation of infection. This step is an important determinant of tissue tropism and pathogenesis; it thus represents a major target for antiviral host cell responses, such as antibody-mediated virus neutralization. Following the development of novel cell culture models for HCV infection our understanding of the HCV entry process and mechanisms of virus neutralization has been markedly advanced. In this review we summarize recent developments in the molecular biology of viral entry and its impact on pathogenesis of HCV infection, development of novel preventive and therapeutic antiviral strategies.     

Suicidal process,suicidal communication and psychosocial situation of young suicide attempters in a rural Vietnamese community

The study aimed to explore the suicidal process, suicidal communication and psychosocial situation of young suicide attempters in a rural community in Hanoi, Vietnam. Semi-structured interviews were conducted, in a community setting, with 19 suicide attempters aged 15-24 who had been consecutively hospitalized in an intensive care unit. In 12 of 19 cases, the first pressing, distinct and constant suicidal thoughts appeared less than one day before the suicide attempt in question. However, distress and mild, fleeting suicidal thoughts had been present up to six months before the suicide attempt in 16 cases. Five respondents had a suicide plan one to three days before attempting suicide. Altogether, 13 engaged in some form of suicidal communication before their attempt. This communication was, however, difficult for outsiders to interpret. Twelve of the respondents were victims of regular physical abuse and 16 had suffered psychological violence for at least one year before attempting suicide. Eighteen of the respondents used pesticides or raticides in their suicide attempts. None sought advice or consultation in the community despite long-standing psychosocial problems. The strategy of reducing the availability of suicide means (e.g., pesticides or raticides) in Asian countries should be complemented with a long-term suicide-preventive strategy that targets school dropouts and domestic violence, and promotes coping abilities and communication about psychological and social problems as well as recognition of signs of distress and suicidal communication.     

果实(种子)化学防御与食果实动物的适应对策

种子植物在果实(种子)成熟后需要防御食果实动物捕食种子,同时要传播种子至适宜萌发的生境。很多植物依赖食果实动物传播种子,称动物传播植物。果实(种子)化学防御是抵御种子捕食者的重要手段。果实(种子)中次生物质包括各种生物碱、生氰糖苷、萜类和酚类等,种类繁多;次生物质的含量随果实成熟过程而变化。次生物质可以抵御动物的捕食,其毒性对种子传播者和种子捕食者没有选择性,即具泛毒性。果肉中的次生物质也可以起到轻泻剂的作用,缩短种子在动物消化道的滞留时间,以影响传播效率。果实(种子)次生物质的产生不受植物环境条件的影响,其产生与果实质量有关。在温带地区,通常SS型果实次生物质含量低,而FL型果实含量高。食果实动物可通过调整捕食行为、摄取环境中特殊物质和获得丰富营养等3个方面适应次生物质。果实(种子)中次生物质的研究对动植物相互作用、协同进化理论具有重要的意义。     

As good as dead? Sublethal predation facilitates lethal predation on an intertidal clam

Although ecologists have speculated that sublethal predation can impact prey dynamics, consequences of these predator effects have seldom been experimentally tested. In soft‐sediment marine communities, fishes crop extended feeding siphons of buried clams, potentially causing clams to reduce their burial depth, thereby enhancing their susceptibility to excavating lethal predators. We simulated cropping of the confamilial clams, Protothaca staminea and Venerupis philippinarum, by removing the top 40% of siphons, which caused each species to burrow 33–50% shallower than conspecifics with intact siphons. To examine subsequent consequences of reduced burial depth, we exposed cropped and intact clams to natural levels of predation in the field. Because of a naturally longer siphon, Protothaca, even after cropping, remained at relatively safe burial depths. In contrast, siphon cropping nearly doubled the mortality rate of Venerupis. Thus, while sublethal predation facilitates lethal predation, this linkage depends on specific life history characteristics, even among ecologically similar species.